1/2" is way to thick. The thickness of glass is relative to the height of the tank and how much bracing you plan to use. With euro bracing and a center brace you can get away with 1/4" though I still wouldn't recommend it. At 16" high you can go rimless at 3/8 thick with no problem. My latest DIY tank is 48x16x16 rimless with 3/8". I have zero bowing of the panels. Anything above 18" high would need bracing and 3/8" thick. 1/2" is super thick and crazy expensive. Hope this helps!